Joint



H. w. GIFFIN Nov. 1, 1938.

JOINT Filed March 25, 1957 I3 Fig.3; /8,

Inventor Harold W. Giff/1'1 a itorney Patented Nov. 1, 1938 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to an improved expansion and contraction joint, that is, a device which serves as a protecting medium for the openings which are placed between substantially abutting surfaces to allow for expansion and contraction of the surfaces. The device is adapted to be used in the construction of roads or highways, sidewalks, walls, fioors of buildings, swimming pools, or any other surface where expansion and contraction occur. It is particularly adapted to and useful in constructing concrete roads and highways where the pavement, constructed on a suitable base, is divided into sections or slabs, said slabs having a space between the substantially abutting sections to allow for expansion and contraction of the concrete under the influence of temperature and moisture changes. The discussion and description of my invention will hereinafter be directed as applied to roads and highways, but the specific description and embodiment shall not be construed as excluding any other of the numerous practical applications of my invention wherever expansion and contraction of surfaces occur.

I-Ieretofore various tread-plate-types of expansion and contraction joints have been used in constructing concrete roads and highways, and although the efiiciences of the previously known joints are not questioned, the joints are complicated in structure and quite cumbersome to handle in the construction work. It will be quite obvious also, that if the joint device is complicated in structure, the cost of manufacturing such joint device will be so high that it will be too expensive for use in general highway or road construction operations.

Thepresent invention has, therefore, for its general object, to improve expansion and contraction joints of the tread-plate variety by substituting for the complicated and expensive de- Vices heretofore used, a device having relatively few parts and in which all elements are sturdy and simplified in structure. In introducing the combination of few working parts and simplification in structure the manufacturing costs of the joint device will be reduced, which has an important bearing upon the highway cost.

Another object of my invention is to create an expansion and contraction joint device in which the elements of the joint have a great deal of flexibility in operation in contrast to a rigid structure. The previously known tread-plate joints are keyed, bolted or wedged together in such a manner that no vertical flexibleness of the device is possible. Such conditions are undesirable and through the application of my invention tojoint devices, these undesirable features are eliminated.

A further object of my invention is to provide a cheap and practical means for preserving a smoothness and continuity of the pavement surface in order that the riding quality of the pavement may not be impaired. In using the previously known rigid joint structures, when wear occurred on the plate supporting ledges or shoulders, the loose plate created undesirable irregularities in the pavement surface as well as noise. Through the use of my flexible and automatically adjusting tread-plate to any normal wear of the concrete slabs, these troublesome features are vitiated.

A still further object of my invention is to prepare a joint device which, through the constant tight fit between the tread-plate and the concrete, will prevent any surface water from draining or flowing into the expansion crevice between the adjacent concrete slabs. The constant positive tension whichis on the tread-plate in my' invention prevents the surface water from draining into the opening, which, as is widely known in the road construction art, is quite difiicult to control. It is generally recognized that when Water enters into the joint space and thence to the sub-grade, the sub-grade beneath the substantially abutting slab ends tends to soften, thereby decreasing the load-bearing power of the sub-grade. Furthermore, it will also be obvious that through the tight fit between the tread-plate and the supporting shoulder, dirt, stones, or other foreign substances will be prevented from depositing in the opening which would ultimately cause spalling.

An additional object of my invention is to construct an expansion and contraction joint device which can be disassembled in a very short time and permits access to the joint space for inspection and repairs. Heretofore, it was oftimes necessary to cut away part of the pavement or joint structure to permit access, but as will be obvious in studying the joint device claimed as my invention, such steps will be unnecessary in using my invention.

Another object of my invention is to design an expansion and contraction joint which can be adapted and" adjusted to irregularities and imperfections of workmanship in the concrete slabs. In using previously known joints of the treadplate variety, considerable care was necessarily exercised in preparing the opening between the slabs of concrete inorder to acquire a perfect fit between the joint device to the concrete. However, through the use of my joint structure, wherein the spring-action, hereinafter described, will compensate for any irregularities in structure or for normal wear action, an assurance of a perfect and tight fit can be obtained under quite extreme adverse irregularities and conditions in structure or wear.

Generally stated, my invention in its broadest physical embodiment consists of a tread-plate, spanning the opening between the adjacent or substantially abutting slabs, and held in place by an anchoring device including a flexible spring means. The spring means exerts a constant or positive pull upon the tread-plate, thereby assuring a tight contact between the plate and the section of concrete supporting the plate. In order that the inventionmay be fully and clearly understood as to its method and principle of operation, and as to the essential features of its physical arrangement, I have illustrated simple and practical forms of the expansion and contraction joint device in the attached drawing which I have found afford satisfactory and de- 5 sirable results in highway engineering activities.

In referring to the drawing:

Fig. 1 is a fragmentary sectional view of a pavement equipped with a joint structure of my invention.

Fig. 2 is a fragmentary sectional view of the joint structure taken along the line 2--2.

Fig. 3 is a fragmentary sectional View of a pavement equipped with a modified form of my joint structure.

Fig. 4 is a sectional view of another modified form of my joint structure.-

Fig. 5 is a perspective View of a pavement structure including a view of the tread-plate and the expansion and contraction device.

U Referring in more specific detail and by reference characters to the drawing, which illustrates preferred embodiments of my invention, fragmentary sections of concrete highways are disclosed equipped with various modifications of --my improved expansion and contraction joint.

In the drawing 'a foundation I0 is disclosed upon which a plurality of separated, but contiguous and aligned pavement sections or slabs II are placed or cast. The sections are spaced sufficiently far apart to allow for the thermal expansion and contraction of the slabs and at the same time to permit the insertion of an expansion and contraction joint.

In my invention, the spaced oposing faces of each pair of concrete slabs II are partially cut 55 away or cast in reduced thickness, in contrast to the thickness of the main body of the slab thereby forming opposing and depressed shoulders I2.

Bridging the space between the slabs II and adapted to rest on the shoulder portions I2 is a rigid. tread-plate IS. The tread-plate is disposed on the shoulders in such a manner that the surface continuity of the highway is maintained, and at the same time allowing adequate space for expansion and contraction of the structure, which space may be filled with a plastic material I8.

The tread-plate usually extends across the pavement as shown in Fig. 5, thereby generally be crete slabs imparting the usual rigidity and strength to the aligned concrete slabs as well as serving as an anchoring medium for the spring bolt I5. One end of the spring bolt I5, is secured to the tread-plate through any suitable means as, for example, in the figures, the bolt or screw I I, is inserted through the apertures of the treadplateand threaded over the threads IS, on the end of the spring bolt I5. The other end of the spring bolt I5 is bent into a loop which is adapted to be slipped over the dowel pins I1, and anchored thereto. 'The constant pull imparted by the spring bolt upon the plate tends to hold the tread-plate in place at all times.

In order to prevent water from seeping into the expansionspace between the spaced concrete slabs, a water-tight seal in the form of a gasket It, is provided between the tread-plate I3, and the supporting shoulder I2. The gasket generally is a fibrous or woven material saturated with a bituminous substance, but rubber or any other water-proofing material may be used. It is understood, however, that the insertion of the gasket between the plate and shoulder is not always necessary, particularly where excellent workmanship in the construction of the shoulders and plate have been followed thereby providing uniform contact of the contacting surfaces. Additional plastic filler I8, preferably a bituminous substance, is placed in the space between the sides of the tread-plate and the walls or edges of the shoulder portion I2. It is also obvious that the plastic filler is not absolutely necessary for the operation of the joint, but it will tend to prevent dirt, grit and water from filling the areas which preferably are kept free. 1

In Fig. 3 a modificationof my spring element joint is shown which operates in substantially the same manner as the joints disclosed in Figs. 1' and 2, but a re-arrangement of the parts make it desirable to disclose and describe the modification. In preparing the concrete slabs II, opposing recesses 26 are placed at the'bottom of the slabs as well'as the opposing shoulders I2 at the top of the slabs. A spring plate 2I having the opposite ends pressingagainst the upper sur- 7 faces of the recesses 26 is held firmly in place by a bolt 20, which is inserted through an opening of the spring plate and anchored to the treadplate I3. The downward pressure exerted by the spring plate against the bolt head 24 will tend to hold the tread-plate securely in place at all times.

Another modification of my invention is disclosed in Fig. 4. The plate 25 has an opening through which the spring bolt 22 is passed, the ends of which are fastened to the tread-plate I3 and the plate 25. The constant positive pull exerted by the coil spring 23 will tend to pull the plate 25 against the upper surface of the recess 26 and also pull the tread-plate I3 toward the shoulders.

It is obvious that through my invention a positive pull is exerted at all times upon the treadplate 63 in the various modifications of my invention. Even though there may be wearing action on the shoulder surfaces, the constant pull on the plate will tend to keep water, dirt, or

other foreign material from entering the space between the spaced concrete slabs. As a further improvement and protection in conjunction with In the above specification a description of the objects of the invention and a detailed discussion of the specific elements of my invention have been given. Obviously, so far as the spring action expansion andcontraction joint is concerned, the details of the structure may be modified from the above shown details. Changes in the form, construction, arrangement and combination of parts may be made and substituted for those herein shown and described, but it is understood that I reserve as a part of my invention all such variations and modifications which fairly fall within the scope and spirit of my claims.

Having thus described my invention, I claim, as follows:

1. In an expansion and contraction joint structure for pavements and the like comprising, in combination with a pair of spaced pavement sections having opposing recessed shoulder portions at the top, a tread-plate having a rigid body portion disposed in spaced relation between the outer edges of and resting on the shoulder portions of said sections, and means including a spring element adapted for engagement with the plate and pavement sections, said means exerting a substantially downward pull and anchoring the tread-plate in place.

2. In an expansion and contraction joint structure for pavements and the like comprising, in combination with a pair of spaced pavement sections having opposing recessed shoulder portions at the top, a tread-plate having spaced apertures and a rigid body portion disposed in spaced relation between the outer edges of and resting on the shoulder portions of said section; and means in-- cluding a spring element adapted for engagement with the plate and pavement sections for anchoring the tread-plate in place, said means engaging the plate through the medium of the apertures in the plate and exerting a substanspring element exerting a substantially downward pull and adapted for engagement with the plate and pavement sections, said means engaging the pavement sections through the medium of said metallic means connecting the pavement sections.

4. In an expansion and contraction joint structure for pavements and the like comprising, in combination with a pair of spaced pavement sections having opposing recessed shoulder portions at the top and opposing recesses at the bottom of the sections, a tread-plate having a rigid portion disposed in spaced relation between the outer edges of and resting on the shoulder portions of said sections, a metallic spring means extending between and disposed in the opposing bottom recesses of the pavement sections, and means adapted to engage the tread-plate and spring means for anchoring the tread-plate in place, said spring v means exerting a substantially downward pull on combination with a pair of spaced pavement sections as defined in claim 1 in which a waterproof gasket is inserted between the tread-plate and the supporting shoulder and a sealing filler is placed between the sides of the tread-plate and the edges of the shoulder. I

6. In an expansion and contraction joint structure for pavements and the like comprising in combination with a pair of spaced pavement sections as defined in claim 2 in which a waterproof gasket is inserted between the tread-plate and. the supporting shoulder and. a sealing filler is placed between the sides of the tread-plate and the edges of the shoulder.

7. In an expansion and contraction joint structure for pavements and the like comprising in combination with a pair of spaced pavement sections as defined in claim 3 in which a waterproof gasket is inserted between the tread-plate and the supporting shoulder and a sealing filler is placed between the sides of the tread-plate and the edges 

